image-fit: Fix signature checking

On signature verification failures fit_image_verify() should
exit with error.

Signed-off-by: Andrej Rosano <andrej@inversepath.com>

common/image-fit.c

@@ -1030,8 +1030,10 @@ int fit_image_verify(const void *fit, int image_noffset)
 					strlen(FIT_SIG_NODENAME))) {
 			ret = fit_image_check_sig(fit, noffset, data,
 							size, -1, &err_msg);
-			if (ret)
+			if (ret) {
 				puts("- ");
+				goto error;
+			}
 			else
 				puts("+ ");
 		}